目的 探讨在线尿素清除率监测(OCM)在血液透析中的应用价值。方法 采用OCM对本中心行维持性血液透析的23例终末期肾衰患者，在透析器F6首次使用及复用第7次时采用OCM检测尿素清除指数(Kt/V)，与同时应用尿素动力学单室可变容积模型计算Kt/V值进行比较并进行相关性分析。结果 透析器首次使用时，OCM检测值（1.25±0.16）低于Kt/V计算值（1.37±0.23），相关性分析显示两者存在显著的直线相关性(r=0.842，p ＜0.001)；透析器复用第7次时，OCM检测值（1.23±0.15）低于Kt/V计算值（1.31±0.17）,相关性分析显示两者存在显著的直线相关性(r=0.667,P＜0.01)；透析器首次使用OCM检测值和复用7次时OCM检测值相比，无显著差异(t=1.908，p＞0.05) ；透析器首次使用Kt/V计算值和复用7次时Kt/V计算值相比，亦无显著差异(t=1.692，p＞0.05)。结论 OCM检测值低于Kt/V计算值，OCM在作为评价尿毒症血透患者血液透析充分性指标时，应注意二者的差别。透析器复用7次不影响对小分子物质的清除。

Objective To evaluate on-line clearance monitoring (OCM) of urea in the assessment of Kt/V during hemodialysis. Methods Kt/V values of 23 maintenance hemodialysis patients treated in this hospital were assessed by OCM and by single-pool urea kinetic model. The Kt/V values by the two methods were compared. The Kt/V values form the patients using the dialyzer for the first time and at the 7th time were also compared. Results In patients who used the dialyser for the first time, the Kt/V values were (1.25±0.16) by OCM and (1.37±0.23) by single-pool urea kinetic model (r=0.842, P <0. 001). In those who reused the dialyser at the 7th time, the Kt/V values were (1.23±0.15) by OCM and (1.31±0.17) by single-pool urea kinetic model (r=0.667, P＜0.01). The Kt/V values from patients using the dialyzer for the first time and those from patients reusing it at the 7th time had no significant differences both by OCM (t=1.908，P＞0.05) and by single-pool urea kinetic model (t=1.692，P＞0.05). Conclusion Kt/V values by OCM are usually lower than those calculated from urea measurements. This difference has to be considered in application of the results to clinical practice. The dialyser reused for 7 cycles still has unchanged clearance ability to small molecule solutes.